This can be for several reasons. Firstly a word can have more than one meaning, and thus the sign changes for each meaning. Also, there can be regional variations on how a sign is presented.

You are missing a sign? I have spotted a wrong sign?

If you would like to send additional video signs that you would be happy to include on this site, please send them to me. If you have spotted any mistakes or errors, please contact me and I will do my best to fix.